The objectives of this project are to isolate and characterize Streptococcus mutans cell components that may exert detrimental effects on host tissue through direct interactions or by immunological mechanisms. In one study, representative strains of S. mutans will be examined for antigens that are shared with human and monkey heart and kidney tissues (CR-antigens). Anti-bacterial sera will be tested for antibodies to CR-antigens by indirect immunofluorescence (IIF), immunoelectrophoresis and indirect radioimmunoassay (IRIA). CR-antigens will be extracted from selected bacteria and purified using a variety of methods, including: gel filtration, isoelectric focusing, polyacrylamide disc gel electrophoresis and affinity chromatography. The effects of streptococcal induced tissue-reactive antibodies will be studied in actively and passively immunized animals. Resulting tissue pathology will be ascertained using both light and electron microscopy. Immunofluorescence, immunoenzyme, immunoferritin and conventional histological stains will be employed. The CR-antigen of animal tissue will be solubilized, and biochemically and immunologically characterized. In a second study, soluble extracts of selected S. mutans cells will be tested for components with direct binding affinity for heart and kidney tissue using IIF and IRIA. The tissue-binding factor (TBF) and the tissue receptor will be isolated, purified, and characterized using the methods described above. The effects of the streptococcal TBF in vivo will be studied by injection of purified material into rabbits. Tissue pathology will be determined with the methods listed above. The effects of streptococcal cell components on tissue at the site of immunization will also be studied. Animals that have been successfully immunized in anti-caries studies will be obtained and their tissues examined for pathology.